Lie and tell her Housecarls have to be female.
Lol, that would be opposite to real life where all houscarls were male.
There were to different words for the two genders as slaves in old Icelandic (and other languages), húskarl (that is, housecarl) for the males and ambátt for the females.
When I first heard I'd be getting a housecarl I was surprised when they offered me Lydia